A technique of a light-receiving device is conventionally disclosed where series connections of a quenching resistance and an avalanche photodiode (APD) are connected in parallel to measure the number of incident photons. An APD is composed of silicon (Si), and hence, it is referred to as a Silicon Photomultiplier (SiPM).
It is expected that an SiPM will be adopted for a distance measurement system that uses a laser diode (LD) as a light source and measures a distance to a measurement object. A structure is proposed for improving a sensitivity of a photoelectric conversion element by thinning a film of a semiconductor substrate or providing a structure where a metal reflective film is provided therein. Furthermore, a structure is also proposed that uses a compound semiconductor substrate in order to improve a light-receiving sensitivity. However, thinning a film of a semiconductor substrate causes a restriction on, for example, formation of a bonding pad or the like, and a configuration that uses a compound semiconductor substrate provides a high cost. Furthermore, in a case where it is used for a distance measurement system, a multifunctional light-receiving device is desired that is also capable of providing distance information in addition to a high light-receiving sensitivity of a photoelectric conversion element. Furthermore, a light-receiving device is desired that is readily manufactured and is capable of reducing a cost thereof.